CHAPTER 9 WATCHDOG TIMER
Preliminary User’s Manual U16898EJ1V0UD
151
9.4.4
Watchdog timer operation in HALT mode (when “low-speed Ring-OSC can be stopped by software” is
selected by option byte)
The watchdog timer stops counting during HALT instruction execution regardless of whether the operation clock of
the watchdog timer is the clock to peripheral hardware (f
XP
) or low-speed Ring-OSC clock (f
RL
). After HALT mode is
released, counting is started again using the operation clock before the operation was stopped. At this time, the
counter is not cleared to 0 but holds its value.
Figure 9-8. Operation in HALT Mode
Watchdog timer
Operating
f
XP
or f
RL
f
CPU
CPU operation
Normal operation
Operating
HALT
Operation stopped
Normal operation
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